Septic arthritis of hip joint

 Young male patient with fever of ~5-6 weeks duration, right hip pain.

STIR Coronal : Green arrow - joint effusion, Orange arrow: asymmetric red marrow / marrow edema.
(See last MRI image also)

STIR Axial image, Grade 3 joint effusion

STIR Axial image, marked.

Thickening and enhancement of the joint capsule / synovial layers.

Ultrasound: Echogenic fluid with debris within the anterior synovial recess. Anterior peri-articular muscle edema+. Probe tenderness+.

Eventhough the T1 hypointense signals in the intertrochanteric region (left) can be explained by the presence of residual red marrow in this 20yr old patient, the signal intensity is markedly reduced on right side, suspicious of marrow edema.

UR- Quiz 1 - (4th June 2018) : What's your diagnosis?

 69y Female. History of  transient loss of consciousness and fall resulting in side of head hitting a window, 2 years back, with slowly progressing swelling in left side of head.

ANSWER HERE...

Ring shaped lateral meniscus

Ring shaped lateral meniscus is a very rare anatomical variant which can easily mimic and make it difficult to distinguish from a bucket handle tear. Unlike the normal C-shape, this variant forms a complete ring.

Usually the lateral portion appears as in normal cases, with angular margins or sometimes can appear deficient anteriorly. The additional medial component appear like displaced torn fragment and easily gets mistaken for a bucket handle tear (where the body of meniscus will be truncated c.f. ring meniscus).

In differentiation from central perforation of a discoid lateral meniscus, the inner margins in central perforation will be irregular with degenerative changes. Associated osteophytes and chondral lesions may also be seen unlike a case of ring shaped lateral meniscus.

Pancreatic pseudocyst with duct communication (CT)

Pancreatic pseudocysts are the most common (85% to 90%) cystic lesions of pancreas, which are encapsulated peripancreatic or remote fluid collections developing after 4 weeks of an episode of acute pancreatitis. These are called pseudocysts as cyst lining is formed of fibrous tissue and not true epithelium. Cyst contents are rich in amylase.

Causes of pancreatic pseudocysts include Acute or chronic pancreatitis (most common), pancreatic trauma and rarely iatrogenic (e.g. partial gastrectomy). In cases of acute pancreatitis with inflammatory changes and seeing fluid collection developing wall or capsule in the peri-pancreatic region in follow-up imaging, is usually diagnostic of a pseudocyst. These usually arise 4 to 6 weeks after an acute episode. Pseudocysts can be followed up if the patient is asymptomatic or the cyst is smaller than 6cm as there is a chance of spontaneous resolution in smaller cysts.¹

Complications include secondary infection, hemorrhage, rupture and mass effect on adjacent structures.¹

Above axial images of contrast CT shows a large, peripherally enhancing cystic area (green arrow) in relation to the pancreas, consistent with a pseudocyst. Yellow arrow points to the pancreatic head head and orange arrow points to the distal CBD.

 

Green arrows mark the pancreatic pseuocyst and blue arrow points to the stretched residual pancreatic parenchyma of body region.


 

Sagittal reformats showing the duct (yellow arrows) in tail region.

Sagittal MPR and Sagittal Minimum Intensity Projection, showing the PD and the pseudocyst.

A communication between the PD and the pseudocyst is demonstated in the above image. 

Cysts communicating with PD are difficult to treat and tend to recur.

Presence of internal dependent debris level is regarded as highly specific for the diagnosis of pancreatic pseudocysts in MRI ².




References:
1. Imaging Diagnosis of Cystic Pancreatic Lesions: Pseudocyst versus Nonpseudocyst
Young H. Kim, Sanjay Saini, Dushant Sahani, Peter F. Hahn, Peter R. Mueller, Yong H. Auh
Radiographics, May 2005.

2. Differentiating Pancreatic Cystic Neoplasms from Pancreatic Pseudocysts at MR Imaging: Value of Perceived Internal Debris.
Michael Macari, Myra E. Finn, Genevieve L. Bennett, Kyunghee C. Cho,
Elliot Newman, Cristina H. Hajdu, James S. Babb.
Radiology April 2009.

3. Radiopaedia.

Plain CT Brain findings in an adolescent patient with Tuberous Sclerosis

Tuberous Sclerosis (TS) or Bournville disease is a rare Autosomal Dominant (AD) neurocutaneous syndrome (phakomatoses) characterized by development of multiple benign tumors of in various organs. Since the characteristic clinical triad mentioned is mental retardation, adenoma sebaceum and seizures is uncommon, imaging plays an important role in diagnosis of this condition.Sometimes intrauterine diagnosis of TS of the fetus can be suspected with visualization of cardiac rhabdomyomas in ultrasound.

Below are some of the features of TS detectable in plain CT, in a 16yr old patient.

Above image shows the presence of characteristic calcified and non-calcified sub-ependymal nodules (red arrows). Calcification of these subpendymal hamartomas is less frequent in early childhood, where as cortical/subcortical tubers can calcify as early as 2yrs of age.

Image showing multiple cortical and subcortical hypodensities suggestive of cortical tubers (blue arrows). Most of the tubers in TS are located in frontal lobe.

Left foramen of Monro region shows a relatively homogenous, non-calcified lesion (blue arrows) measuring AP dimension of ~13mm - suspicious of a Subpendymal Giant Cell Astrocytoma (SGCA / SEGA). These are considered WHO-Grade 1 tumors, eventhough there is a potential of causing obstructive hydrocephalus. These are theorized to evolve from the subpendymal nodules. Histologically both SGCA and subpendymal hamartomas show same appearance.SGCAs can show intense enhancement, and may show calcifications and heterogeneity.

Same lesion in sagittal reformat (golden arrow).

A few calcified cerebellar tubers (green arrows).

Above bone window images show multiple calvarial
small sclerotic areas of hyperostosis (orange arrows).